Is this the bar exam? Like many things, it would be complicated, touching on both civilian and military law. Short answer, her Commanding Officer IS her Commanding Officer until relieved of command. If it was her responsibility to issue such a contract (of course you know that with the GSA, that's not they way things work on base, but it's a hypothetical so we'll let it slide), and she did so in good faith, then yes, the contract would probably be upheld, irrespective of any looming changing of command, rumored or otherwise.
However, if she were aware or reasonably should have been aware that there was something "improper or illegal" afoot between this contractor and your commanding officer, things could get very sticky and there would be multiple issues that would need to be litigated. How it would turn out, would be anyone's guess.
No man's life, liberty, or property are safe while court is in session...
[apologies to Mark Twain]
OK, so make it a developmental item.